When a cylindrical electrophotographic photoreceptor (hereinafter occasionally referred to as a photoreceptor drum) is produced, a coating layer is generally formed by immersing a conductive cylindrical substrate into into a photosensitive layer composition or coating compositions for an interlayer and a surface protective layer.
In such a case, since the conductive cylindrical substrate is immersed into a coating composition, a coating layer is formed on the entire surface of the conductive cylindrical body. When a photoreceptor drum, which is subjected to formation of the coating layer on the entire surface, is mounted on an electrophotographic image forming apparatus, occasionally, it becomes impossible to accurately carry out hitting due to peeling of the coating layer through contact with rollers which hits development units. Further, occasionally, it becomes impossible to use the photoreceptor drum as a contact point for grounding. As a result, it is preferable to remove the coating layer adhered on both edges of the photoreceptor drum.
Methods for removing such a coating layer include a method in which edges of a photoreceptor drum are immersed in a solvent and is subjected to vibration employing ultrasonic waves (Japanese Patent Application Open to Public Inspection No. 63-311357), a rubbing method employing a brush (Japanese Patent Application Open to Public Inspection Nos. 3-60782, 4-141663, 5-142789, 10-207084, 11-184100, and 11-194509), and in addition, a removing method employing tape.
For example, a method (Japanese Patent Application Open to Public Inspection No. 6-138670) is known in which tape which is comprised of thermally fusible type nonwoven fabric is successively unwound, and the resulting tape is impregnated with solvent and thereafter, the impregnated tape comes into contact with a photoreceptor drum, thereby the removal is carried out. A method (Japanese Patent Application Open to Public Inspection No. 9-281725) is also known in which tape comprised of nonwoven fabric, having an uneven structure on one surface, is employed.
Based on the investigations performed by the inventors of the present invention, however, in any methods, the following problems were found. Edges of the coating layer of a photoreceptor drum, in which the coating layer had been removed, tended to peel off. Insufficient cleaning occurred due to accumulation of toner at the edges in which the coating layer had been removed and toner scattering occurred, resulting in staining of the interior of the apparatus. Due to those, durability of the photoreceptor drum as well as cleaning member (such as cleaning means) degrades. As a result, it has been demanded that edges of the coating layer are shaped so that such problems do not occur.
Current electrophotographic image forming apparatuses, which are widely employed on the market, comprise at least charging, image exposure, development, transfer and cleaning means as well as a fixing means at the periphery of the electrophotographic photoreceptor as an image bearing body.
A charging member, which has been employed as a representative member for the aforesaid charging means, is a corona discharge unit. The corona charging unit exhibits advantages in which stable charging is carried out. However, since it is necessary to apply high voltage to the corona discharge unit, a large amount of ionized oxygen, ozone, moisture, and oxidized nitrogen compounds is generated. As a result, electrophotographic photoreceptors are degraded and human body may be advisedly affected.
Therefore, currently, it has been investigated to utilize a contact charging system instead of using the corona discharge unit. Specifically, a magnetic brush or a conductive roller is subjected to voltage application and subsequently comes into contact with a photoreceptor which is a charging body, whereby the photoreceptor surface is charged to the specified electric potential. When such a contact charging system is employed, it is possible to decrease voltage as well as an ozone generation amount, compared to the non-contact type charging system employing the corona discharge unit.
Accordingly, the contact charging units, which decrease the amount of ozone generation, have been increasingly employed. However, since the photoreceptor surface is subjected to abrasion, during repeated image formation, the photosensitive layer is abraded, whereby excessive rubbing as well as peeling at the edges of the coating layer occurs.
Particularly, during the repeated use at high temperature and high humidity, toner is adhere-accumulated at the edges of the photoreceptor, whereby the torque between the cleaning blade and the photoreceptor varies, resulting in peeling of the coating layer at edges. Particularly, when peeling occurs, or coagulated toner which adheres to the aforesaid portion is mixed with developer as foreign matter, insufficient charging as well as insufficient cleaning results in black spots, whereby image quality is occasionally degraded.
Particularly, in recent years, in order to utilize excellent image quality which is an advantage of the electrophotographic image forming method, and to further improve the image quality, development toner, comprised of smaller size particles with uniform shape, has been commonly employed. In such cases, the aforesaid problems are more pronounced.